Clutch drum and method for manufacturing such clutch drum

Abstract

A clutch drum for a multi-plate clutch in an automatic transmission is provided at an inner periphery thereof with splines by which friction plates are engaged. Each of the splines has a tooth tip having two circumferential ends. Only one of the circumferential ends of the tooth tip has a curved surface. The splines of the clutch drum may be formed by form rolling using a tooth forming tool including a tooth root. The tooth root may have a circumferentially leading end and a circumferentially trailing end in a rotational direction, with only the circumferentially leading end having a curved surface.

1. A clutch apparatus comprising:
 a clutch drum provided at an inner periphery thereof with splines; 
 first rotary plates each of which is provided at an outer periphery thereof with teeth engaging said splines; 
 second rotary plates arranged alternately with said first rotary plates in an axial direction; and 
 a piston for applying an urging force in order to frictionally engage said first rotary plates and said second rotary plates with each other, 
 wherein each of said splines has a tooth tip having two circumferential ends, only one of said circumferential ends of the tooth tip having a curved surface, and 
 an oil path through which oil flows is bounded by said curved surface. 
 
   
   
     2. A clutch apparatus according to  claim 1 , wherein a tooth side surface adjacent to the other of said circumferential ends of each tooth tip is used as a torque transmitting surface. 
   
   
     3. A clutch apparatus according to  claim 1 , wherein the other of said circumferential ends of said tooth tip has a substantially right angle corner. 
   
   
     4. A clutch apparatus according to  claim 1 , wherein said first rotary plates are friction plates and said second rotary plates are separator plates. 
   
   
     5. A clutch apparatus according to  claim 1 , wherein said oil path is defined between said curved surface and a surface portion of one of the first rotary plates, said surface portion being opposed to the curved surface and being of non-complementary configuration with respect to said curved surface.